The present invention relates to metal extrusion, and particularly to a production method and its corresponding mold for the extrusion of aluminum alloy heat sinks with extra high profile ratios.
The speed of computer devices has continuously increased with a resulting increase in the heat given off within these devices. While electric fans can be used to cool CPUs and other computer devices, they have the disadvantage of introducing dust into the computer. This dust deposits over the CPUs and the surfaces of heat sinks, influences the radiation of heat and accelerates the aging of integrated circuits and the like. In extreme cases, the dust may lead to a short circuit and destruction of the device. Therefore, an alternative method for the removal of heat is desired. Heat sinks with high profile ratios can be used as an alternative to fans.
Aluminum alloy heat sinks are used to radiate the heat away from computer devices without the use of fans. To increase the heat removal capacity of the heat sink, the radiating surface area is increased. This is done by increasing the radiating fin height and decreasing the spacing between fins. This ratio of fin height to fin spacing is the profile ratio.
Using traditional solid plate type molds, aluminum alloy heat sinks with a profile ratio of less than five can be produced. Using a combined mold, which is a combination of a hollow mold and a solid mold, aluminum alloy heat sinks having profile ratios of up to six to ten may be produced. Currently, heat sinks having a profile ratio of ten approach the limit that can be produced with this method. This limit is based on the increased fin length and close fin spacing of the heat sink, which requires correspondingly long and thin sections in the mold. As the mold sections become longer and thinner, the cross-sectional area of the mold section, and its yield strength, decreases. Starting around a profile ratio of ten, the design strength of steels available for these long, thin mold sections is exceeded, leading to destruction of the mold. Until now, it has been very difficult for the world wide aluminum extrusion industry to overcome the problem of producing molds capable of extruding heat sinks with extra high profile ratios. Therefore, there is a need for a method and mold design which is capable of producing heat sinks with extra high profile ratios.